Study on Nitrogen Removed from Leachate by the Aged Refuse Bioreactor

摘要

The bioreactor, filled with aged refuse, was used to remove different nitrogen compounds from refuse leachate, by means of injection in the laboratory. The research is focused on the efficiency, main influencing factors and biological mechanism of nitrogen removed from the leachate. It is indicated from the findings that in case of injection period of 12h, injection quantity of 0.5L, and CODcr concentration of 6000mg/L in influent, the NH3-N concentration in leachate is reduced from 195-2000mg/L to 5-20mg/L, with a removal efficiency of over 93%, meanwhile, that TN removed up 82%. The nitrogen removal is influenced mainly by such factors as BOD5/TN of influent, oxidation-reduction conditions of the bioreactor, operation temperature of the bioreactor and pH of influent. When the BOD5/TN is higher than 1-3, the Eh more than 100mV, the temperature approximate to 30℃, and the pH to 7, the bioreactor is able to achieve a satisfied nitrogen removal efficiency. A biological mechanism of nitrogen removal is proved to mainly be a joint action of nitrosification, nitrification, aerobic denitrification and anaerobic denitrification. Based on the inference of biofilm on the aged refuse particles, processes of nitrosification and nitrification are mainly accomplished on surface of the particles, while processes of aerobic denitrification and anaerobic denitrification mainly accomplished in the aerobic layer and the anaerobic layer of the biofilm, respectively. The research gives guidance in achievement of economical and effective nitrogen removal of leachate.